In certain fields of application such as, for example, the liquefaction of natural or synthetic gas of low boiling point, installations, are known in which the condensation of the gas at high pressure and at low temperature and then the supercooling of the liquefied gas at high pressure are obtained by passing through cryogenic generators, followed by the expansion of the gas as a continuous flow through a pressure-reducer in order to collect the liquefied gas, for example in a low-pressure receptacle.
The cryogenic generators generally consist of bundles of coiled tubes which have the disadvantage of being large in size and relatively costly.
Other known installations employ plate bundles arranged in a leakproof vessel and comprising a stack of plates which are parallel to one another to form a first circulation circuit for the gas under pressure and a second circulation circuit for a liquid under pressure, concurrent with the first circuit.
To avoid damaging the plate bundle, the latter must be blocked either by an external pressure which is higher than or equal to the highest pressure capable of existing in the plate bundle or by a mechanical pressurization such as a sheet-and-tie-rods assembly, or by a combination of both these systems.
Thus, all the operating conditions, i.e., normal operation, start-up, shutdown and the exceptional cases of operation, must be envisaged so as to guarantee the mechanical behavior of the plate bundle.